Chrome, which only recently grabbed the number three spot from Apple's Safari, ended January with a share of 5.2 percent, up 0.6 of a percentage point.

The increase, although slightly less than Chrome's jump during December, was the browser's second-largest since Google debuted the program in September 2008. Chrome has doubled its share since July 2009.

IE, meanwhile, lost half a percentage point to end January with a share of 62.2 percent, another record low in a long decline that cost Microsoft's browser 10 percent of its share in the past year alone.

If IE maintains the pace of the last three months, the browser will slip below the 50 percent mark in April 2011.

Firefox's share also dropped in January, the second monthly decline in a row. This was only the second time in more than two years that Firefox had lost ground in two consecutive months.

Firefox ended January down 0.2 of a percentage point, to 24.4 percent. According to NetApplications, Firefox has yet to hit the magic 25 percent mark, having come closest in November 2009 before growth stalled.

Although Firefox 3.6, which Mozilla released on January 21, grew by 0.7 of a percentage point and ended the month with a 1.1 percent share, the new version's launch couldn't stem the losses for the open-source browser overall.

Safari's share was up slightly, to 4.5 percent, while Opera Software's desktop browser was down slightly to 2.4 percent.

The newer IE7 also again fell, losing 1 percentage point and finishing January with a 14.6 percent share. Both declines were somewhat under the torrid pace of the last three months, when each edition lost more than a point per month.

IE8, the browser Microsoft issued in March 2009, captured some but not all of its siblings' losses: IE8 ended January with a share of 22.3 percent, up 1.5 points.

When NetApplications accounted for IE8's 'compatibility view' - a feature that lets users display sites as rendered by the older, and often web standard-incompatible IE6 and IE7 - Microsoft's newest browser owned a 25.1 percent share, making it the most popular single edition of any browser by a five-point margin.

The persistent decline of IE has long been a bane to Microsoft and a boon to rivals. But in the last two months, Firefox - normally the browser to reap the most from IE's fall - has been shoved aside by the newcomer Chrome.

Over the last three months, Chrome has outgained Firefox by 5:1, posting an increase of 1.62 points to Firefox's 0.32 point.

Even over a longer run, Chrome has boosted its share more than Mozilla's: Over the last 12 months, Chrome has gained 3.68 points, Firefox 2.3 points.

Chrome has already met the first goal that Google set last year when the browser's engineering director said Chrome would own 5 percent of the market by September 2010, and 10 percent by September 2011.

If Chrome can keep up the pace it's made during the last three months, it will break the 10 percent mark in November, 10 months ahead of schedule.

NetApplications.com measures browser usage share by collecting systems data from the computers that visit the 40,000 sites it monitors for clients.